SECT. 3] 



DYNAMICS OF OCEAN CLTIRENTS 



347 



(1957) advanced an alternative explanation of the discrepancy by pointing out 

 that a])preciable barotro])ic flow could be maintained by sinking of water in 

 polar regions. The barotropic How would be concentrated into a western 

 boundary current in the same way as the stress-driven baroclinic flow. In the 

 Atlantic Ocean the barotropic flow would be directed opposite to the Gulf 

 Stream. Evidence to support his arguments was found by Swallow^ and 

 Worthington (1957) who measured a strong reverse flow under the Gulf Stream. 

 The effect of the barotropic flow is to reduce the total transport of the Gulf 

 Stream to values that are in closer agreement with those obtained from wind 



1.17 



1.00 



0.80 



0.60- 



0.40 



0.20 



0.00 



Fig. 2. The function T(^)^l-ei/^ cos {V3^/2)- (l/V3)e-if^ sin (V3^/2) obtained as a 

 solution of the frictional boundary-layer equations at the western boundary, where 

 ^ = x/W and W^ = (^///^)'/3. The mass-transport function is proportional to T{^) in 

 the boundary region. 



stress. According to Stommel, the barotropic flow continues across the equator 

 and re-enforces the weaker baroclinic flow observed off the coast of Brazil. 

 Thus, although the baroclinic transport is more strongly developed in the 

 North Atlantic, the total transports are about the same order of magnitude in 

 both the North and South Atlantic. Stommel's explanation of the discrepancy 

 is plausible for the Atlantic Ocean. However, it is not so convincing when 

 applied to the Kuroshio. There are no sources of deep water in the North 

 Pacific Ocean so that the barotropic flow, if present, should be directed the 

 same as the Kuroshio. Stommel and Arons (1960) have suggested that part of 

 the difficulty may be eliminated by taking the spherical geometry of the earth 

 into account instead of using the j8-plane approximation. If this is done, it is 



